When a mutual capacitance touch detection scheme is applied to a handheld terminal device, particularly to a mobile phone product, errors of initialization establishment benchmarks may often be caused because a palm presses a large area of a touch screen or another object contacts a large area of a touch screen during initialization. Even if the palm or object is removed, a persistent key-pressing operation may be wrongly detected, which may cause that normal user operations are unable to be responded. A typical problematic scene is that: a mobile phone, with the LCD thereof being in a non-display situation, is grasped by a hand of a user or put in a pocket of the user; when a call suddenly comes in, the LCD is lighted up, but the user finds that the mobile phone cannot be unlocked and the call cannot be answered. At present, all mutual capacitance schemes, including iphone, have this problem. Another situation is that: on the premise of a normal initialization benchmark, a large palm presses a normally working touch screen, and a persistent key-pressing operation may be wrongly detected after the palm is removed, which may cause that user operations are unable to be responded.
The above-mentioned misdetection phenomenon is mainly caused by the reason that the difference data characteristics detected by multiple fingers, even by a single finger, in normal situations is very similar to the difference characteristics detected when the benchmark has been updated under the condition of pressing a large area and the pressure is removed. Therefore, it is unable to distinguish between normal multiple finger touches and “misoperation points” formed after pressing a large area.